1. Field of the Invention
The present invention relates to systems and methods for protecting vehicle occupants from injury. More specifically, the present invention relates to a dual flow inflator that injects multiple gas flows into an airbag system, such as an inflatable curtain.
2. Description of Related Art
The inclusion of inflatable safety restraint devices, or airbags, is now a legal requirement for many new vehicles. Airbags are typically installed in the steering wheel and in the dashboard on the passenger side of a car. In the event of an accident, an accelerometer within the vehicle measures the abnormal deceleration and triggers the expulsion of rapidly expanding gases from an inflator. The expanding gases fill the airbags, which immediately inflate in front of the driver and passenger to protect them from impact against the windshield. Side impact airbags, known as inflatable curtains, have also been developed in response to the need for protection from impacts in a lateral direction, or against the side of the vehicle. An inflatable curtain may have one or more separately inflated cushions.
Side impact cushions are often designed to unfold or unroll downward to inflate beside a person to keep the person from hitting the door or window during lateral impact. Since a vehicle occupant may be leaning forward, reclined in the seat, or at any position between, such cushions are often made somewhat long to ensure that the occupant hits the cushion. If multiple cushions are fed by a single inflator positioned either fore or aft of the cushions, an especially long gas flow path exists between the inflator and the cushion furthest from the inflator. Thus, the outermost extents of the inflatable curtain may receive insufficient inflation gas pressure to inflate to the optimal protective pressure.
Even with somewhat shorter cushions, rapid and even inflation can be difficult to achieve with known inflator designs. Many existing inflators eject inflation gases outward radially; consequently, the inflation gases are not propelled along the length of the cushion, but are directed into the cushion near the inflator. The outer regions of the cushion are still inflated later than those closest to the inflator.
Additionally, some inflatable curtain systems are somewhat expensive due to the need for multiple inflators, attachment mechanisms, and the like. Many inflatable curtain systems require the use of a gas conduit that conveys gas from the inflator to the inflatable curtain. Some known inflators require the use of multiple initiators that add to the manufacturing expense and timing requirements of the inflator.
Furthermore, many inflators produce thrust upon activation. As a result, somewhat complex attachment mechanisms must often be used to affix the inflators to the vehicle to ensure that the inflators do not dislodge themselves during deployment. Such additional parts increase the cost of the inflatable curtain system, as well as the time and expense required to install the inflatable curtain system in a vehicle.
Yet another shortcoming of current inflator designs is the difficulty of customizing the inflator for attachment to inflatable curtains of varying types and sizes. For example, an SUV may require two generally large inflatable curtains for each of the front and rear seats. However, a sports car may require a medium-sized inflatable curtain for the front seat and a small inflatable curtain for the rear seat. In order to accommodate different inflatable curtain requirements, unique inflator configurations are needed in for different vehicles.
Accordingly, a need exists for an inflator and related methods that remedy the problems found in the prior art. Such an inflator should preferably provide relatively even and rapid inflation of the associated inflatable curtain, preferably without requiring multiple inflators for a single curtain. Such an inflator should also preferably be simple and inexpensive to manufacture and install.
Furthermore, it would be an improvement in the art to provide an inflator that could simultaneously inflate two differently sized inflatable curtains. It would be a further improvement in the art to provide an inflator capable of inflating two differently sized inflatable curtains, while still remaining substantially thrust neutral. Another improvement in the art would be to provide an inflator module capable of receiving differently sized gas vessels that can be customized for an individual automobile. Such an inflator and inflatable curtain system is disclosed herein.